Oil typically includes acid components as impurities. The acids are both naturally occurring in oil and are generated as the result of chemical reactions, such as oxidation. The acid components can cause deterioration of oil, odors, and corrosion of equipment used at the site of pumping, refining, transfer, and storage. One such deleterious acid is naphthenic acid, and methods of reducing naphthenic acid have been proposed. For example, U.S. Pat. No. 5,182,013 discloses a method for diluting an oil including a large amount of naphthenic acid with an oil having a relatively small amount of naphthenic acid. U.S. Pat. No. 4,199,440 discloses treating liquid hydrocarbons with a dilute basic solution including sodium hydroxide, or the like.